Known air compressor devices for supplying compressed air to a vehicle air suspension device are described in the U.S. Pat. No. 6,074,177 and Japanese Patent Laid-Open Publication No. Hi 1(1999)-264375. This air compressor device includes a motor portion serving as a driving power source, a piston crank portion connected to an output shaft of the motor portion, a piston that generates compressed air, and a drier portion for removing water and/or moisture drops from the air compressed by the piston crank portion.
The motor portion and drier portion of air compressor devices are arranged in parallel with each other onboard the vehicle. The known air compressors further include the piston crank portion being connected, at a first end, to the motor portion and, at a second end, to the drier portion so that the vehicle air compressor device forms an approximately U shaped unit when the motor portion, piston crank portion and drier position are connected to each other.
There is a demand for improving the throughput efficiency of the design by standardizing the design as much as possible so that the air compressor device can accommodate various vehicle characteristics. In order to meet this demand, a design flexibility is required. Although the motor portion and the drier portion are arranged in parallel with each other and the motor portion is mounted with the drier portion of the air compressor device, a size reduction and simplification of the components are needed due to the space limitations and/or dimensions of vehicles.
Further, a design should be capable of modification in response to different specifications of the vehicle's air compressor device, for example, a stroke of the piston has to be changed so that the volume of the supplied, compressed air can be modified. Among the known counter measures taken in order to meet the foregoing specification requests on the device, the center of mass of the motor device and the center of mass of the drier portion are moved away from each other and so the length of the piston crank provided between the motor device and the drier portion gets longer. This can increase vibrational loads in the on-board environment, for example, the motor device and the drier portion are more affected by vibration from the vehicle body. Further, because the motor device and the drier portion comprising the main portion of the air compressor device are likely influenced by vibration, a structure with high vibration resistance has been required.
A need thus exists for a vehicle air compressor device which meets a design standardization requirement including high performance on vibration resistance and downsizing.